The present invention relates to high speed generators and, more particularly, to high speed generators used with gas turbine engines such as those used in aircraft, tanks, ships, terrestrial vehicles, or other applications.
A generator system for a gas turbine engine, such as that found in aircraft, may include three separate brushless generators, namely, a permanent magnet generator (PMG), an exciter, and a main generator. The PMG includes permanent magnets on its rotor. When the PMG rotates, AC currents are induced in stator windings of the PMG. These AC currents are typically fed to a regulator or a control device, which in turn outputs a DC current. This DC current next is provided to stator windings of the exciter. As the rotor of the exciter rotates, three phases of AC current are typically induced in the rotor windings. Rectifier circuits that rotate with the rotor of the exciter rectify this three-phase AC current, and the resulting DC currents are provided to the rotor windings of the main generator. Finally, as the rotor of the main generator rotates, three phases of AC current are typically induced in its stator, and this three-phase AC output can then be provided to a load such as, for example, an aircraft electrical system.
Some of the mechanical components within the generator rotate and thus may be supplied with lubricant. In addition, some of the electrical components within the generator may generate heat due to electrical losses, and thus may be supplied with a cooling medium. The lubricating and cooling media may be supplied from different systems, or from a single system that supplies a fluid, such as oil, that acts as both a lubricating and a cooling medium. In either case, the systems used to supply the lubricating and/or cooling media may not sufficiently lubricate and cool all of the rotating and electrical components within the generator housing. In addition, the flow of oil through the generator may result in some of the oil being preheated by some components before flowing to and through various other components. Moreover, the structure of the generator cooling system may not allow the generator to be connected to the lubricating and cooling system in alternate configurations.
Hence, there is a need in the art for a generator lubricating and cooling system that sufficiently lubricates and cools all of the rotating and electrical components within the generator housing, and/or does not significantly preheat the cooling medium, and/or allows the generator to be connected to the lubricating and cooling system in more than one configuration. The present invention addresses one or more of these needs.
The present invention provides an improved high speed generator with a lubricating and cooling oil system. In one embodiment of the present invention, and by way of example only, a high speed generator includes a housing, a rotor shaft, a rotor assembly, a stator assembly, a substantially hollow rotor shaft, at least one rotor cooling supply port, at least one rotor cooling return port, an oil supply conduit, at least one rotor assembly cooling flow path, an oil return conduit, and at least one stator cooling flow path. The rotor shaft is rotationally mounted within the housing. The rotor assembly is mounted on the shaft. The stator assembly is mounted within the housing and surrounds at least a portion of the rotor assembly. The substantially hollow rotor shaft is rotationally mounted within the generator housing, and has a first end, a second end, an outer circumferential surface, and an inner circumferential surface. The at least one rotor cooling supply port is positioned proximate the rotor shaft second end and extends between the rotor shaft inner circumferential surface and the rotor shaft outer circumferential surface. The at least one rotor cooling return port is positioned proximate the rotor shaft first end and extends between the rotor shaft inner circumferential surface and the rotor shaft outer circumferential surface. The oil supply conduit is coupled to the generator housing and has an inlet end in fluid communication with a pressurized oil source and an outlet end extending a first predetermined distance into the hollow rotor shaft. The at least one rotor assembly cooling flow path extends through the rotor, and has an inlet end in fluid communication with each rotor cooling supply port and an outlet end in fluid communication with each rotor cooling return port. The oil return conduit is coupled to the generator housing and surrounds at least a portion of the oil supply conduit, the oil return conduit has an inlet end extending a second predetermined distance into the hollow shaft and an outlet end in fluid communication with the rotor cooling return port. The at least one stator cooling flow path is positioned adjacent the stator and has an inlet in fluid communication with the oil return conduit second end and an outlet in fluid communication with a supply oil return path.
In another exemplary embodiment, an end bell for coupling to a high speed generator includes a housing, a first fluid inlet port, a second fluid inlet port, a first fluid outlet port, a second fluid outlet port, a substantially hollow oil supply conduit, a substantially hollow oil return conduit, a first flow path, and a second flow path. The supply conduit has an inlet end coupled to the housing and an outlet end extending a first predetermined distance from the housing. The oil return conduit surrounds at least a portion of the oil supply conduit and has an inlet end extending a second predetermined distance from the housing and an outlet end coupled to the housing. The first flow path extends through the housing and is in fluid communication between the first and second fluid inlet ports and the supply conduit inlet end. The second flow path extends through the housing and is in fluid communication between the first and second outlet ports and the return conduit outlet end.
In yet another exemplary embodiment, a high speed generator, includes a housing, a rotor shaft, a rotor assembly, and a stator assembly. The housing has at least two ends. The rotor shaft is rotationally mounted within the housing on at least two generator bearings. The rotor assembly is mounted on the shaft. The stator assembly is mounted within the housing and surrounding at least a portion of the rotor assembly. A path for fluid communication is provided to the generator on either end of the housing that directs a lubricating and cooling medium to the housing, and a portion of the lubricating and cooling medium is supplied to generator bearings, and a remaining portion then flows through the rotor shaft, through the rotor, back to the rotor shaft, through the stator, and out of the generator.
Other independent features and advantages of the preferred generator lubricating and cooling system will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.